Trouble in paradise? Vishnu/FFtec N54 335ii Single Turbo kits experiencing issues as a BimmerBoost member runs 12.5@121 with misfires and having to short shift

Trouble in paradise? Vishnu/FFtec N54 335ii Single Turbo kits experiencing issues as a BimmerBoost member runs 12.5@121 with misfires and having to short shift

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Trouble in paradise? Vishnu/FFtec N54 335ii Single Turbo kits experiencing issues as a BimmerBoost member runs 12.5@121 with misfires and having to short shift

BimmerBoost would like to thank member GeorgiaTech335Coupe for his openness and honesty regarding his Vishnu/FFTEC single turbo setup. Recently, this member took his single turbo upgraded 6-speed manual 335i to the PBIR (Palm Beach International Raceway) dragstrip in Florida to do some testing. His best run was a 12.50@121.6 alongside a 12.8@117. Yes, these times are quite a ways away from the 10.8@131 glory pass from Vishnu demonstrating the kits capability.

This is in no way the fault of GeorgiaTech335Coupe who experienced misfires on his car and had to short shift at 6300 rpm in order to avoid them. Now, Vishnu has basically portrayed this kit as perfect and ready for sale with nobody having any issues. The reason BimmerBoost is bringing this issue to the attention of the community is for potential buyers to understand what they are getting into.

There is absolutely nothing wrong with having issues when modifying a car to this level and BimmerBoost is confident Vishnu will resolve them. There is something wrong with pretending nothing is wrong. A few cars with the single turbo kits have gone up for sale and apparently a total of three people, that are willing to open their mouths, are having misfire issues with these kits.

These issues will no doubt get resolved but potential buyers and current customers needs to be aware of the process, effort, and that progress is being made. Pretending nothing is wrong and collecting money simply is the wrong way to go about this and once again (it's becoming a trend) BimmerBoost is the only site bringing these issues to the attention of the community.

For the record, a member by the name of @tmo335tt says he has a hardware solution for the misfires that he will likely share with Vishnu (hopefully not for free). Interesting that it isn't Vishnu but the community solving this.

Thanks again to @GeorgiaTech335Coupe for sharing his details, good or bad, as we all learn thanks to honesty and openness. There is more to tuning than just collecting money.

IIRC Shiv put the O2 sensors in the primaries of the mani pre-turbo and the N54(like a lot of engines) uses the O2 sensors as part of the misfire detection system. I'm thinking because the sensors are only really seeing exhaust gas from one cylinder of each bank it's thinking there i a misfire.

Let's just say at x degrees of crank rotation it expects to see x AFR becuase cylinder x would've just fired, however it sees y AFRs and it thinks something's wrong in cylinder x.

Could be something to keep in mind.

The FFTEC manifold merges from 3 into 1 on each bank, with the o2 sensor on single pipe - so it sees afr from all 3 cylinders per bank.

My car has this misfire issue as well, it is currently taken apart because I'm replacing the lifters to see if there is a possibility that one is binding on cyl6. (unfortunately my work schedule isn't leaving me much time to work on the car at the moment)

If any of the ST guys want to run their cars to redline and see what it should feel like without going into limp mode, reset your adaptations and while the car is running in open loop you will not get a misfire or limp....as soon as it goes back to running closed loop all of your problems will return.

This has to be the most frustrating problem pertaining to the N54 and I'm about ready to throw in the towel.

If anyone is interested in ST car that isn't running properly and they feel like they can fix it shoot me an offer I bought the car and turbo kit mainly to have fun at shift sector. I didn't want a single turbo on my 335 AT so I bought another 335 with a MT and put the turbo on over the next couple of days so that it would be ready for the race and unfortunately it was not because of the misfire issue. I don't need two 335's.

In vast majority of cars the misfire detection is based upon "sudden" crank slowdown making the DME think combustion was incomplete (i.e. misfired). I think it may be possible that a sudden change in boost (a sudden drop) where the crank would suddenly slow down a bit under WOT (and anything associated to it) may be at fault here which trips the DME's misfire threshold. With heat build-up in the high RPM range on higher gears this may be a possibility and something I haven't considered before.

EDIT: What sort of throws off the above theory is that the misfire is ALWAYS registered against bank2, always!

In vast majority of cars the misfire detection is based upon "sudden" crank slowdown making the DME think combustion was incomplete (i.e. misfired). I think it may be possible that a sudden change in boost (a sudden drop) where the crank would suddenly slow down a bit under WOT (and anything associated to it) may be at fault here which trips the DME's misfire threshold. With heat build-up in the high RPM range on higher gears this may be a possibility and something I haven't considered before.

EDIT: What sort of throws off the above theory is that the misfire is ALWAYS registered against bank2, always!

I don't think so. I have seen datalogs of charge pipes blow off mid pull and that's about the biggest sudden drop in boost/power i can imagine and the only code or complaint is the drop in power and associated P30FF and limp mode. No mentions of a misfire.

If we knew the misfire algorithm/trigger conditions this would be much easier to trace. DAMN YOU SIEMENS!!! lol

I don't think so. I have seen datalogs of charge pipes blow off mid pull and that's about the biggest sudden drop in boost/power i can imagine and the only code or complaint is the drop in power and associated P30FF and limp mode. No mentions of a misfire.

If we knew the misfire algorithm/trigger conditions this would be much easier to trace. DAMN YOU SIEMENS!!! lol

I was at the PBIR rental on Sunday and had the opportunity to talk to GeorgiaTech335Coupe and JMARS. Both are cool guys and GeorgiaTech335Coupe was helping me figure out some issues I was having with my car. I can imagine the frustration and hope everything gets figured out for them sooner, rather than later.

In vast majority of cars the misfire detection is based upon "sudden" crank slowdown making the DME think combustion was incomplete (i.e. misfired). I think it may be possible that a sudden change in boost (a sudden drop) where the crank would suddenly slow down a bit under WOT (and anything associated to it) may be at fault here which trips the DME's misfire threshold. With heat build-up in the high RPM range on higher gears this may be a possibility and something I haven't considered before.

EDIT: What sort of throws off the above theory is that the misfire is ALWAYS registered against bank2, always!

DZ I saw you were commenting in another thread that Robb@cobb and you have been going back and forth with others on this topic, that the knock sensors aren't the issue and that it's something internal to the DME that seems to be the cause. I tend to believe this after all other relevant troubleshoot steps have been taken (put stock plugs/coils/etc back in, try different tune etc).

I've read around some other platforms and this misfire detection monitor has been around as long as OBD-2 and lots of weird things have set it off for those platforms. Given the N54 is a straight 6 and as a result has an unusually long crank, I would if the torsional vibrations seen at high rpm/power are that much worse that it's showing up in the CPS enough to piss off the DME.

It could be a zillion different things- non-stock clutch and flywheel, malfunctioning engine accessory causing intermittent crank loads via accessory belt, oil pump vibrations/fluctuations (air bubbles etc) and even just stupid electrical interference somehow disturbing the output of the CPS or the CPS itself could just be bad. Yeesh. Anything that mucks with the CPS signal could cause it but if that were the case, could we not watch/record the CPS signal with a scope and see if it's changing shape when the problem happens?

DZ I saw you were commenting in another thread that Robb@cobb and you have been going back and forth with others on this topic, that the knock sensors aren't the issue and that it's something internal to the DME that seems to be the cause. I tend to believe this after all other relevant troubleshoot steps have been taken (put stock plugs/coils/etc back in, try different tune etc).

I've read around some other platforms and this misfire detection monitor has been around as long as OBD-2 and lots of weird things have set it off for those platforms. Given the N54 is a straight 6 and as a result has an unusually long crank, I would if the torsional vibrations seen at high rpm/power are that much worse that it's showing up in the CPS enough to piss off the DME.

It could be a zillion different things- non-stock clutch and flywheel, malfunctioning engine accessory causing intermittent crank loads via accessory belt, oil pump vibrations/fluctuations (air bubbles etc) and even just stupid electrical interference somehow disturbing the output of the CPS or the CPS itself could just be bad. Yeesh. Anything that mucks with the CPS signal could cause it but if that were the case, could we not watch/record the CPS signal with a scope and see if it's changing shape when the problem happens?

I've changed the CPS sensor. Recently with my top end build I've also changed out the oil pump CPS is definitely involved but we don't know if there are other things as well until that part of the DME is wide in the open and we know what exactly makes it tick. This is why I very strongly suggest to people with this issue to just turn it off for the time being until that part of the DME is exposed instead of wasting their time/money with the car instead of enjoying the newfound power toys

I think before you turn it off you should eliminate normal causes, like injector spray pattern, as those will melt a piston quickly.

Yes, for sure, first change the usual suspects: coils, plugs, injectors, in that bank2 at least, make sure you've got the clips on the injectors and they're seated properly. Once you're past those and its still happening, well...

I've changed the CPS sensor. Recently with my top end build I've also changed out the oil pump CPS is definitely involved but we don't know if there are other things as well until that part of the DME is wide in the open and we know what exactly makes it tick. This is why I very strongly suggest to people with this issue to just turn it off for the time being until that part of the DME is exposed instead of wasting their time/money with the car instead of enjoying the newfound power toys

When you had your engine out did you replace lifters and valve springs?

When you had your engine out did you replace lifters and valve springs?

All new springs both sides. Lifters need to have a certain dip on their face to be deemed bad. All of mine were perfectly flat and I didn't want to change them. Keep in mind all of these misfires are in bank2, all the time. Its very unlikely its a bad lifter but if you're inclined to change them out go for it. I don't suggest it as I really doubt its the case.

In vast majority of cars the misfire detection is based upon "sudden" crank slowdown making the DME think combustion was incomplete (i.e. misfired). I think it may be possible that a sudden change in boost (a sudden drop) where the crank would suddenly slow down a bit under WOT (and anything associated to it) may be at fault here which trips the DME's misfire threshold. With heat build-up in the high RPM range on higher gears this may be a possibility and something I haven't considered before.

EDIT: What sort of throws off the above theory is that the misfire is ALWAYS registered against bank2, always!

One thing you are making me wonder, has anybody with the misfire problem ever duplicated the problem with a SMFW installed? I just ask because I notice that on hard shifts I seem to get several samples of rpm oscillation on the Cobb logger before it settles out again. I assume it due to the DMFW oscillating. In my low-power case that seems to cause more sensitive knock readings but I don't have the misfire issue. But since I have seen it affect the ECU, I'm just wondering if anybody with a SMFW has ever had your misfire issue? The DMFW will allow a lot more instantaneous change in rpm.

One thing you are making me wonder, has anybody with the misfire problem ever duplicated the problem with a SMFW installed? I just ask because I notice that on hard shifts I seem to get several samples of rpm oscillation on the Cobb logger before it settles out again. I assume it due to the DMFW oscillating. In my low-power case that seems to cause more sensitive knock readings but I don't have the misfire issue. But since I have seen it affect the ECU, I'm just wondering if anybody with a SMFW has ever had your misfire issue? The DMFW will allow a lot more instantaneous change in rpm.

Shiv is running a single mass, FBIS is running a single mass flywheel. AFAIK they don't misfire. My issues have all been with the DMFW in place as my single mass flywheel from CM went before putting on RB turbos as far as I remember. I'll have to double check though.

However, if that were indeed the case, why ONLY and ALWAYS bank2!

EDIT: Another funny thing since we're on it, both Shiv and FBIS run a 3.46 rear end!